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On January 13, 2018, a false ballistic missile alert that lasted 38 minutes was issued across Oahu, Hawaii, United States. As a result of a system failure, an erroneous text message was sent that stated, “Ballistic missile threat inbound to Hawaii. Seek immediate shelter.”

Aim:

The research team wanted to know the degree of reported anxiety triggered by the event and if knowledge, attitudes, or behaviors for individual/family emergency preparedness (EP) changed post-event.

Methods:

A 50-question survey that asked about individual and family EP pre- and post-event, and the level of anxiety triggered by the event, was administered to a convenience sample of full-time adult residents of Oahu. The study was conducted over a 6-8 week period post-event. Statistical analysis was used to identify factors associated with an increasing level of EP post-event and reported event-triggered anxiety.

Results:

209 participants completed the survey (29% male, 71% female) with about one half living with children. One third were essential workers. Key factors that correlate with increasing various areas of EP post-event include higher educational, receipt of electronic emergency alerts, prior emergency training, and higher reported connectedness to community. Those with higher event anxiety were more likely to develop and practice an EP plan post-event, encourage EP with friends, and report a higher level of community connectedness. The elderly were more likely to have higher levels of EP before and after the event but were less likely to receive emergency alert notifications or have EP training.

Discussion:

While the event was very unfortunate, it did seem to stimulate citizen disaster EP among some groups. Additional research should explore the utility of increasing EP education for communities immediately after disasters, tailoring this education for groups, and targeting the elderly for participation in the emergency alert system.

The only way to deduce information from stars is to decode the radiation it emits in an appropriate way. Spectroscopy can solve this and derive many properties of stars. In this work we seek to derive simultaneously the stellar and wind characteristics of a wide range of massive stars. Our stellar properties encompass the effective temperature, the surface gravity, the stellar radius, the micro-turbulence velocity, the rotational velocity and the Si abundance. For wind properties we consider the mass-loss rate, the terminal velocity and the line–force parameters α, k and δ (from the line–driven wind theory). To model the data we use the radiative transport code Fastwind considering the newest hydrodynamical solutions derived with Hydwind code, which needs stellar and line–force parameters to obtain a wind solution. A grid of spectral models of massive stars is created and together with the observed spectra their physical properties are determined through spectral line fittings. These fittings provide an estimation about the line–force parameters, whose theoretical calculations are extremely complex. Furthermore, we expect to confirm that the hydrodynamical solutions obtained with a value of δ slightly larger than ~ 0.25, called δ-slow solutions, describe quite reliable the radiation line-driven winds of A and late B supergiant stars and at the same time explain disagreements between observational data and theoretical models for the Wind–Momentum Luminosity Relationship (WLR).

Rotational speed is an important physical parameter of stars: knowing the distribution of stellar rotational velocities is essential for understanding stellar evolution. However, rotational speed cannot be measured directly and is instead the convolution between the rotational speed and the sine of the inclination angle vsin(i). The problem itself can be described via a Fredhoml integral of the first kind. A new method (Curé et al. 2014) to deconvolve this inverse problem and obtain the cumulative distribution function for stellar rotational velocities is based on the work of Chandrasekhar & Münch (1950). Another method to obtain the probability distribution function is Tikhonov regularization method (Christen et al. 2016). The proposed methods can be also applied to the mass ratio distribution of extrasolar planets and brown dwarfs (in binary systems, Curé et al. 2015).

For stars in a cluster, where all members are gravitationally bounded, the standard assumption that rotational axes are uniform distributed over the sphere is questionable. On the basis of the proposed techniques a simple approach to model this anisotropy of rotational axes has been developed with the possibility to “disentangling” simultaneously both the rotational speed distribution and the orientation of rotational axes.

In the frame of radiation driven wind theory (Castor et al.1975), we present self-consistent hydrodynamical solutions to the line-force parameters (k, α, δ) under LTE conditions. Hydrodynamic models are provided by HydWind (Curé 2004). We evaluate these results with those ones previously found in literature, focusing in different regions of the optical depth to be used to perform the calculations. The values for mass-loss rate and terminal velocity obtained from our calculations are also presented.

We also examine the line-force parameters for the case when large changes in ionization throughout the wind occurs (δ-slow solutions, Curé et al.2011).

We build a 2D model of the radiative envelope of main sequence massive stars. We set a dynamical boundary condition at the bottom of the radiative envelope at η = rC/R (where rC is the core size and R the radius of the star) to account for the differential rotation of the convective core as computed in 3D simulations (e.g. Browning et al. (2004, IAUS, 224, 149). We seek the differential rotation and associated meridional circulation induced by such a shear competing with the baroclinic flow of the stably stratified radiative envelope using the Boussinesq approximation.